Regarding a transparent substrate such as glass or plastic, when a substrate surface is at a temperature of dew-point or lower, minute water droplets adhere to the surface and scatter transmitted light, which impairs transparency, resulting in what is called “fogging”. As means for preventing fogging, various proposals have been made hitherto.
Specifically, there are known (1) method to lower the surface tension of adhering water droplets by treating the substrate surface with a surfactant, (2) method to make the substrate surface hydrophilic by adding a hydrophilic property to the substrate surface by using a hydrophilic resin or a hydrophilic inorganic chemical compound, (3) method to maintain the substrate surface to a temperature of dew-point or more by installing a heater or the like on the substrate and heating by it, (4) method to provide a water absorbing resin layer on the substrate surface and remove the minute water droplets formed on the substrate surface by absorption, and/or reduce atmospheric humidity on the substrate surface, and the like.
However, by the above method (1) or (2), a water film is formed on the formed film surface and a change occurs easily in appearance due to occurrence of distortion, forming water droplets, and/or the like when it is retained for a long period in a high-humidity environment, and also a sticky feeling when used may be felt somewhat unpleasant. Further, in the method of (3), the antifogging performance can be sustained semipermanently, but the energy accompanying supplying electricity is constantly needed, and thus it is very costly. On the other hand, the method of (4) is regarded as a particularly excellent method as means for preventing fogging because excellent antifogging property can be exhibited without requiring running costs, in addition to that it causes no change in appearance and its sense of use is often appreciated due to that no water exists on the surface.
As such antifogging technology of (4) utilizing a water absorbing compound layer, specifically, an antifogging article having an antifogging film in which a low water absorbing cross-linking resin layer and a high water absorbing cross-linking resin layer are layered sequentially on a substrate surface has been proposed (see Patent Reference 1 (JP-A 2008-273067)). The antifogging film described in Patent Reference 1 is an antifogging film having both antifogging property and durability. However, it has a problem of impairing appearance when it is attempted to further increase the durability for use in applications requiring high durability. Accordingly, an antifogging article having an antifogging film which excels in antifogging property and having both durability, such as abrasion resistance and peeling resistance, and good appearance has been demanded.